Rabble furnace



April 28, 1925.

A. N. J ETTE RABBLE FURNACE 1923 5 Sheets -Sheet 1 Filed July 16 April 28, 1925. L535A'50 A. N. JETTE RABBLE FURNACE Filed July 16, 1923 3 Sheets-Sheet 2 A. m. JETTE RABBLE FURNACE Filed.July 16, 1923 3 Sh'eets -Sheet 5 QUA c114.

l mented Apr. 28, 1925.

ARCHIE NOEL JET'TE, OF ANACOND l init ated IVZONTANA.

RABIBLE FURNACE.

Application filed July 16, 1923. Serial No. 651,895.

To-aZZ 10710772 it may concern.

Be it known that l, 'Anonm NOEL Jn'r'r a, a citizen of the United States, residing at Anaconda, in the county of Deer Lodge and State of Montana, have invented certain new and useful Improvements in Rabble Fun naces, of which the following is a specification.

This invention relates to metallurgical roasting or dryingfurnaces of the multiple hearth rotatingshaft type, and more particularly to the rabble arms thereof.

All existing types of rabble arms constructed of cast iron for furnaces using air or water as a cooling medium havea cored chamber into which the water or air is admitted and circulated to keep the arms cooled.

Arms of this type have several drawbacks:

1. In serviee'leaks often develop which cause wastage of the cooling; medium, arm breakage, rapid corrosion of arms and rabbles, .great inconvenience in operation and frequent furnace shut-downs.

2. Sediment from the cooling medium (usually water) settles in the arm chamber and gradually fills it to such an extent as to cause the circulation of the cooling medium to be greatly retarded or stopped entirely. With the circulation retarded or stopped, the arm is heated to such an extent that it sags, bends or breaks, and must be replaced by a new one.

The arms become tightly wedged or corroded in the holder so that it is often exceedingly dillieult to remove them. The operation of removing a rabble arm sometimes consumes two or three days,.and often such great force is required to carry it out that the central shaft or the arm holder, or both, are distorted. Before a new arm can be inserted, it is always necessary to thoroughly clean out the arm holder, and often considerable work must he done on the central shaft and arm holder before the new arm can he put in place. This procedure causes long delays and shut-downs of the furnace which are inimical to the furnace operations.

it is the principal object of the invention to provide a rabble arm construction that eliminates the disadvantages referred to.

For a full understanding of the invention reference is made to the accompanying drawings in which Fig. l is a fragmentary vertical sectional yiew of a roasting furnace embodying the invention;

Figs. 2, 3 and f are vertical sections on an enlarged scale through a rabble arm along section lines 2-2, 3 3, and 4 l, respectively, in Fig. 1;

Big. 5 is a sectional view of a detail in Fig. l; and Figs. 6, 7 and 8 are a plan view, vertical section and end view, respectively, of the inner end of the rabble arm and the rabble arm holder.

Roasting furnaces of the oitferent types are so well known that for the sake of simplicity only a relatively small fraction of a furnace it) is shown, 11 being' the usual hearths,.12 and 13 the openings near the outer and inner ends of the hearths respectively, and Lt indicating; a part of the central shaft on which the rabble arms 15 are carried.

The construction disclosed represents primarily the solution of two problems. in the first instance it prevents injury to the rabble arm proper, and secondly it prevents injury to the mounting.

The desired result is obtained by providing a continuous steel pipe 16 in the castiron arm 15. The pipe 16 extends from the inner end of the rubble arm to near the outer end and returns to the inner end where the free ends are provided with couplings ii for connection with the feed standard 18, and the return (not shown).

The pipe 16 is preferably made of two sections joined at the outer end inasmuch as a single pipe could not be bent to the desired curvature without injury to the mate rial. in practice, 1 bend a p or two separate pipes to provide curvatures of about 8 radius, then saw through the curved portion or portions substantially or nearly parallel with the main portions, and then OX- weld the joining ends. In this way the crosssectional-area is increased and no coupling or union is necessary. The arm is cast around the pipe to make a solid ano riaz'id construction, as clearly seen .in Figs. 9. S and 4.

Inasmuch as the pipe 11 av be of good quality, it forms a skeleton the arm throughout its length, fords a do; ;e of strcn ti against considerably in excess 0" arms of the usual prior constructions. Conversely, the casting of the arm may be much lighter, and in fact a decidedly smaller amount of metal is used than heretofore for the arm proper.

. The amount of metal and the cross-sectional configuration of the arm may be easily so chosen as to combine the requisite mechanical strength with the desired degree of cooling effect. As appears from Figs. 2, 3 and 4, the pipe sections are disposed in a vertical plane through the main portion of the arm, which disposition increases mechanical strength and at the same time provides a large external surface, and a fair distribution of the cooling effects. The incoming water passes through the upper and hotter portion of the arm, and returns through the lower portion whereby the rate of absorption of heat causes a uniform cooling of the arm.

Intermediate the ends of the pipe are preferably provided expansion sleeves 19 in superposition, and separated from each other by spacers 20 which may be welded to the sleeves. As indicated in Fi 5, both sections of the pipe 16 are cut to provide expansion spaces 21. While the inner sections have atight lit in the sleeves, the outer sections have a loose fit, but a suitable packing 22 between the pipe and the sleeves prevents leakage. It is needless to say that the packing should be of heat-resisting material, such as asbestos, in order to retain its sealing effect. By this arrangement the movability of the connection will be preserved indefinitely, and the pipes may expand and contract under the varying furnace conditions.

The arm is mounted in an arm holder 23, which itself is generally of theusual form and may be attached to the center shaft in the usual way as by rivets or bolts 24;. However, I attach the arm in a special manner, principally in conformity with the general disposition as to the cooling pipes, and also partly in order to facilitate the attachment and detachment of the arm.

The end 15 of the arm has its upper portion cut away providing an inwardlytapering or sloping surface 15 the ends of the pipe being disposed in the lower portion and in a horizontal substantially parallel spaced relation. Through the end 1. extends a vertical slot 25 between the pipes 16. lhe arm holder 23 has apertures 26 in vertical alignment and disposed to be substantially in alignment with the slot 25 when the arm 15 is approximately in its proper position in the holder.

A wedge 27 has a beveled surface co-operating with the sloping surface 15 of the end of the arm, and supplements the end 15 to lit into the preferably cylindrical space of the holder. The wedge 27 has likewise an aperture 28 substantially in alignment with the apertures 25 and 26. tapered key 29 is passed through the different apertures and then drawn up to force the wedge and the end 15 into wedging action.

In order to obtain a. secure fit, the inner wall of the slot 25 is tapered, and the lower portion thereof and the outer wall of the slot 2? are so disposed that the key 29 can freely pass downwardly only sufliciently to bring the latter into wedging action against the wedge 27 and the end 15. The key 29 may be drawn up in any suitable manner. I preferably provide the lower end of the key with a screw 30 to receive a nut 31 by means of which and the usual washer 32, I may draw up the key.

In order to conveniently detach the arm from the holder, l. have provided a second slot 33 in the key between the two pipe sections. The key 29 may be knocked out and placed into the slot 33 to exert a wedging action against the inner end of the end portion 15 which is preferably slightly tapered to readily start the key into place. The key, which then bears against the end of the arm and the end of the arm holder, may be given a few taps to loosen and retract the wedge 27, whereupon the arm may be taken out of the holder.

inasmuch as there is no danger of leak, no corrosion can take place between the coir tact surfaces of the wedge 27 and the end 15, or between the key 29 and the contacting parts. The parts may therefore be dis assembled quickly, and without diliiculty, while the connection may be absolutely cure and permanent.

I also propose an improved construction of a lute ring. In the past lute ring castings have often been broken due to unequal expansion and contraction, the lute ring being subjected to greater heat than the lute ring holder. I propose to obviate the difficulty and the expenses incident to the repeated breaking by mounting the lute ring in its holder without any securing means. As indicated in Fig. l, the lute ring has a portion 3% loosely mounted in the lute ring holder 35 so that it may expand and contract independently thereof.

ll hile this feature is not specifically related to the rabble arm holder, it contributes, in a measure, to the same end, i. e. helps to reduce the annoying interruptions of the operation of a furnace due to breakage caused by the expansions and contractions of the metal parts exposed to the varying conditions of temperature. u

Elimination of rabble arm troubles would not afford a full measure of protection if the diiliculties in regard to the lute ring are left, and for this reason, the latter problem forms in reality a part of the larger problem llll which has to do with eliminating expensive interruptions of service in general.

I am fully aware that continuous pipes through rabble arms have been used in the past, and I am also aware that pipes or at least sections thereof, have been previously placed into the rabble arm castings, I do not claim any novelty aside from that particularly pointed out in the claims.

I claim:

1. In a roasting furnace, the combination with a central shaft, of a rabble arm comprising a casting extending through the Wall of the shaft and a continuous pipe for circulation of a cooling medium extending through the casting and terminating at the inner end of the arm, the casting solidly surrounding the pipe.

2. In a roasting furnace, the combination with a central shaft, of a rabble arm comprising a rabble-supporting portion, an end portion extending through the wall of the central shaft, and a continuous pipe for circulation of a cooling medium extending through the said portions and terminating at the inner end of the said end portion, the said portions consisting of a casting solidly surrounding the pipe.

3. In a roasting furnace, the combination with a central shaft, of a rabble arm comprising a rabble-supporting portion, an end portion extending through the wall of the shaft and a continuous pipe for circulation of a cooling medium extending through the said portions and terminating at the inner end of said end portion, the pipe having sections intermediate the ends lying in a substantially vertical plane and the sections at the inner end lying in spaced relation in a substantially horizontal plane.

4. Rabble arm according to claim 3 in which the said portions consist of a casting solidly surrounding the pipe.

In a roasting furnace, the combination with a central shaft, of a rabble arm comprising a rabble-supporting portion and an end portion extending through the wall of the central shaft, a rabble arm holder attachable to the shaft and defining a horizontal channel adapted to receive the end portion, the end portion of the arm being tapered, a wedge co-operating with the tapered portion to fill the space and means drawing'the wedge into wedging position and securing the same, and a continuous pipe for circulation of a cooling medium extending through the said portions and terminating at the inner end of the said end portion.

6. Arrangement according to claim 5 in which the rabble arm holder, the wedge and the said end portion have substantially aligned apertures and the means for drawing and securing the wedge comprises a taper d key, the aperture through the end portion passing between the pipe sections.

7. Arrangement according to claim 5 in which the said portions consist of a casting solidly surrounding the pipe.

8. In a roasting furnace, the combination with a central shaft, of a rabble arm comprising a rabble-supporting portion, an end portion extending through the wall of the central shaft, a continuous pipe for circulation of a cooling medium extending through said portions and terminating at the inner end of said end portion, the pipe having sections disposed in avertical plane intermediate the ends of the arm and in a substantially horizontal plane in said end portion, a rabble arm holder defining a channel to receive the said end portion, the arm holder and the said end portion having substantially aligned slots in a plane between the pipe sections and a key passing through the slots to lock the arm in the holder.

9. Arrangement according to claim 8 in which the said portions consist of a casting solidly surrounding the pipe.

10. In a roasting furnace, a rabble arm containing a continuous pipe terminating at the inner end thereof for circulation of a cooling medium and including an expansible section intermediate the ends of the arm, the arm consisting of a casting solidly surrounding the pipe.

In testimony whereof, I affix my signature.

ARCHIE NOEL JETTE. 

